Function sioul_colour_tables 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn sioul_colour_tables(
    profile: *const u8,
    length: usize,
    calmer: i32,
    cube_size: usize,
    cube: *mut f32,
    curve_size: usize,
    curve: *mut f32,
) -> i32

The tables for cpp/screencolours.cpp: the profile’s length bytes (none when null), how calm (0, 1, 2), and where to write them: cube_size³ × 4 floats at cube, curve_size × 4 at curve, which must be CUBE and CURVE. Returns 1 when written, 0 when they would change nothing, -1 when the profile cannot be used (then nothing is written), -2 for other sizes.

Safety

profile holds length bytes, or is null; cube and curve have room for what is said above.